A power amplifier is essential to a wireless communication system, a medical system, a power device, an audio system, a military radar system and other devices, and its main function is to amplify the power of a transmitted signal. These devices set a relatively high requirement on the power. For example, the power of the wireless communication system is tens or hundreds of watts, the power of the medical system can reach thousands of watts, and the power of the radar device may be as high as several thousands of watts. To reach such high transmission power, a large-power power amplifier is required to amplify it, and the transistor, as a core device of the power amplifier, is responsible for the amplification and the output of all power. However, due to the limitation of the working power of the amplifier, not all the amplified power is output as a useful signal. For example, in an ordinary communication system, only 40% of the power is output as the useful signal of the power amplifier and 60% of the power exists in a form of heat. A small part of the heat may be transferred to the air around so as to avoid causing a big impact on the system; while a large part of the heat is concentrated in the tube core of the power amplifier and the devices around it, such as a ceramic capacitor and an aluminium electrolytic capacitor, which may approach or exceed an acceptable critical temperature easily, and too much heat may affect the performance index and the service life of these devices and cause a significant damage to the reliability of the system.
At present, the heat dissipation way of a large-power transistor in a traditional communication device is as follows: as shown in FIG. 1, which is a diagram of a traditional transistor heat dissipation device in a power amplifier, a transistor is welded on a Printed Circuit Board (PCB) which is fixed on a copper substrate; a source metal at the bottom of the transistor is welded on the copper substrate, and then the copper substrate is fixed on the shell of the device. Usually, heat-conducting glue may be coated or a heat-conducting gasket or other contactants may be added between the copper substrate and the shell of the device. Heat is transferred from the tube core to the copper substrate through the source metal and then to the shell of the device or a heat dissipation fin through the heat-conducting glue and finally forms heat exchange with the environment around.
The heat resistance between the power transistor and the shell of the device may be affected in various aspects. For example, the welding effect of a tube, the heat resistance of a power amplifier copper substrate, the uniformity of the heat-conducting glue and the like may increase the heat resistance, so that the heat transferring efficiency is low, heat cannot be conducted out in time, and the tube core of the transistor has a very high temperature after achieving heat balance. Moreover, the heat may be conducted to other devices on the PCB quickly to heat them, thereby affecting their performances and service lives. Furthermore, many heat dissipation fins are arranged on the shell of the device so as to increase the volume of the whole device and reduce the competitive advantage.
Peltier effect is called a second semiconductor thermoelectric effect, and a thermocouple refrigeration device manufactured based on this effect has been applied to many fields of this industry and has many advantages. For example, the thermocouple refrigeration device is fast in refrigeration and heating, compact in structure, light in weight, noiseless and reliable, achieves a temperature control tolerance within ±0.1° C., and can achieve a temperature difference of more than 100° C. after being cascaded in multistage etc. However, all the refrigeration devices are externally used as accessories at present so that additional purchase and installation are required. Especially, the refrigeration devices are not applied to the heat dissipation of the large-power power amplifier.